Jessica starts counting at 42, and she counts by threes. If 42 is the 1st number that Jessica counts. what is the 12th number that she counts?
Explanation: What is the first number that she counts? $42$ What is the second number that she counts? $\begin{align*}&42 + 3 \\ &= 45\end{align*}$ What is the third number that she counts? $\begin{align*}&42 + 3 + 3 \\ &= 42 + (2 \times 3) \\ &= 48\end{align*}$ What is the 12th number that she counts? $\begin{align*}&42 + (11\times3) \\ &= 42 + 33 \\ &= 75\end{align*}$